Swelling members have been secured to mandrels in a variety of way. One way is to mount the swelling member on a longitudinally split base and secure the base to the mandrel by closing the split base around the mandrel and inserting a long tapered pin. The swelling material itself is secured to the base with adhesives or other chemical bonding techniques. Illustrative of this design is U.S. Pat. No. 7,730,940.
Another technique is to use rigid rings secured to the mandrel on either end of the sealing element to hold it in position as shown in US Publications 2010/0116496 and 2009/0229816. Yet another way is to shrink fit or create tension in the element adjacent the mandrel in an effort to hold it in position and prevent leak paths along the mandrel and element interface. These concepts are illustrated in U.S. Pat. Nos. 7,441,596 and 7,681,653.
Other designs couple end retention with booster devices to enhance the radial seal force applied beyond the swelling such as by sliding a wedge under the swelling element from at least one end. An example of this design is U.S. Pat. No. 7,552,768. Flexible stacks of notched rings have been disposed at opposed ends of a swelling element with a through bolt extending through the element to pull the end ring stacks toward each other. This is shown in US Publication 2010/0038074. Sometimes the swelling material is located in an inflatable to assist the inflatable in holding a seal as shown in U.S. Pat. No. 7,597,152. Other multi-layered designs of swelling sealing systems are shown in U.S. Pat. No. 7,422,071 and US Publication 2009/0178800.
This design uses a single or series of undercut profiles, slots or retentive groove in the mandrel ID or OD depending on where the material is to be retained. The undercut profile allows for greater mechanical retention of the plug material resisting displacement while experiencing a pressure differential.
The present invention addresses the issue of annular seal or tubular plug retention against pressure differentials in a simplified manner using features of the mandrel or the surrounding tubular and positioning the material adjacent to the mandrel surface formation which can be in the form of a projection or depression or a combination so that the material is better retained against pressure differentials when sealing at a subterranean location. The materials can be shape memory materials or swelling materials. These and other aspects of the present invention will be more readily understood by those skilled in the art from a review of the description of the preferred embodiment and the associated drawings while understanding that the full scope of the invention is to be found in the appended claims.